This invention relates to heat stabilized aromatic polycarbonate compositions which are resistant to yellowing during heating due to the incorporation of cyclic carbonates or 1,2-carbonate compounds and organophosphorous compounds.
It is known from U.S. Pat. No. 3,888,817 dated June 10, 1975 that polyester resins can be stabilized against the loss of molecular weight by adding a cyclic carbonate and an antioxidant such as a phenol, phosphite or an amine. However, the reference does not suggest the application of these cyclic carbonates to polycarbonate resin nor does it indicate any reduction in the yellowing of the resins.
It is known from U.S. Pat. Nos. 4,066,611 and 4,076,686 that polycarbonates can be heat stabilized with additives which include epoxy compounds.
It is also known from Ser. No. 370,698, filed Apr. 22, 1982 that polycarbonate resins can be heat stabilized by the addition of cyclic carbonates or 2-keto-1,3-dioxolane compounds. The compositions of the instant invention are rendered more heat stable by the incorporation of organophosphorous compounds.